Gear Basics Pdf

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There are wide applications of spur gears as mentioned below. Circular pitch p - circular pitch is the distance measured on the pitch circle between any two similar points on adjacent teeth. As previously discussed it is assumed that all contact occurs along the pressure line between two points where the addendums of the two mating gears intersect. During unwinding of string from circle, consider the path created by one fixed point of string and that path created by fixed point of string will be considered as involute circle. Therefore spur gears are not preferred in driving mechanism of vehicle such as car.

If two involute profiles were in contact it could also be seen that the generating lines would be tangent to both cylinders, which is the same as the pressure line. This is calculated as the circumference of the base circle divided by the number of teeth. Newer Post Older Post Home. By Mnj Nataraj and Shanmugasundaram Sankar. With lots of advantages of using planetary gear system, there are various applications of planetary gear system and few of them are as mentioned below.


Theoretical calculations are usually based on the pitch circle. Major and minor losses in pipes. In simple, we may say that a planetary gear unit will be compact, higher torque density, lower inertia and generally grease lubricated gearing system. This can then be used in many calculations such as the determination of tooth thickness Ti at different radii, using the equations below.

Usually the pressure line and angle will vary in operation unless there is perfect conjugate action. Hydraulic fluid properties. If there are three planet gears, then planetary gear unit will have three times torsional stiffness as compared to similar size of traditional gear train. In case of planetary gear system, we can increase the torque density by using more planet gears between the sun gear and ring gear. Let us see why we need to say such gearing arrangement as planetary gear system?

Dynamic Effects When two gears are running at high speed it is found that the load experienced by those gears is increased. The contact ratio is now defined as the ratio of the Arc of Action to the circular pitch. It should be intuitive to note that the addendum of one gear in a pair should not be larger the dedendum of the other pinion since this would cause the gear tooth to imbed into the pinion body. We have discussed in our previous post about the types of bevel gears and we have also seen the concept of worms and worm gears.

So before going ahead, i will request to my readers to find out the gear terminology in our previous post. There are two types of spur gears used in industries i. Before understanding the concept of spur gear, we must understand the each term used in gear drive mechanism and we have already discussed it i.

As we are aware that planets move around the sun in universe and in similar manner, two or more than two gears rotates around the central gear in such gearing arrangement. Following image, which is taken from arrowgear, historia de la vida privada duby pdf indicates involute profile of gear meshing with each other where left gear is shown as driver member and right gear is displayed here as driven member. Planetary gear system has lots of advantage as compared to traditional gearboxes. Gear Basics The purpose of this section of the literature review is to gain an understanding of the basics of gear contact and the nomenclature used in the gear industry.

Basics - How Gears Work

Advantage and disadvantage of worm gear and bevel gears. Electric hydraulic thrusters working principle.

Let us consider one spur gear and one planetary gear unit of similar size. Below is a graphical representation of a spur gear and the terms present will be described further.

PDF) Gear basics

Working principle of milling operation. Interference can also occur in gears leaving mesh after the ideal position. Practically this indicates that contact is occurring between the tip of one tooth and the flank of the other, and hence contact is not occurring on the involute profile.

By taking the point at which meshing occurs as a, and the point where meshing ends as b, two more points can be obtained. There are following disadvantages of using spur gear as mentioned here. Planetary gear system has lots of advantages that we have discussed above. Applications of planetary gear system. This is also true with a larger addendum on the pinion, where the pinion tooth would imbed into the gear body.

In order to secure the uniform motion and transmission of power between drive and driven member, surface of tooth of spur gear teeth will have an involute profile. We will discuss here the difference between positive and non-positive displacement pump with the help of this post.

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PDF) Gear basics

Planetary gear system will have following components as mentioned below. If there are four planet gears in planetary gear unit then in that situation, we will secure four times torque transmission capacity as compared to that of spur gear unit.

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Higher torsional stiffness is very important in various applications of repeatability requirement and precise positioning especially under varying loading situations. There are following advantages of using spur gear as mentioned here. Planetary gear is one type of epicyclic gear which could be used where we need precise motion control. The term conjugate refers to the angular velocities of two gears in mesh and conjugate action occurs when these velocities remain constant throughout the meshing cycle. From this information it is now possible to define and calculate the contact ratio with the use of the circular pitch p.

At any point during this unwinding it can be seen that the generating line string at that point is at a tangent with the cylinder and is normal to the involute curve. Its derivation and mathematical description are given below.

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At the end of the mesh cycle the opposite occurs and the driver digs into the driven gears flank. Therefore central gear is termed as sun gear and gears those are rotating around the central gear are termed as planet gears. It can be calculated from the number of teeth N and the pitch circle diameter d in the form.